There are several approaches for liquid level sensing including capacitive, ultrasonic, magnetic, and mechanical solutions. Modern linear 3D Hall sensors allow us to measure the level of a liquid using a single sensor. This document covers a single-sensor implementation of liquid level sensing using a float arm and 3D linear hall sensor. The document discusses the design principles behind a Hall-based liquid level demo using the TMAG5273 linear 3D Hall-effect sensor, a float, and a magnet.